snapping alternator belts...

[bobnewbury]

When I had a new engine fitted (a mermaid melody II) it came with a piddly little 45 A prestolyte alternator. Not a lot of good for charging 450 AH of domestics @ 24v. I retrieved the 75A AC7 from the old engine, had it serviced, and got the (very good) engineer to mount it in addition to the prestolyte and then ran the two through an Adverc.

Results - lots of lovely amps galloping into the batteries. The problem is that the toothed belt which runs the AC 7 from the PTO keeps stripping its teeth, even though I upgraded it to the strongest one I could get hold of. Lasts about 30 hours before giving up the ghost.

I've tried removing the AC 7 and getting it checked over - good as new the man says. The alignment of the belt has been double checked.

Any ideas, anyone?

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[sailorman]

i think u r overloading the belt.
what belt did u use on the old engine & was the Adverc fitted to it

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[LadyInBed]

Is the belt driving anything else?
If it is a long belt, then it will have a lot of whip in it, if so, you could consider putting in an idler pulley, maybe one that follows the flat (back) of the belt. This would also increase the contact radius on the other pulleys.


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[Mudplugger]

Possibility of twin belts on twin pulley's??... TW/

<hr width=100% size=1>Tony W.

 

[Born_Free]

You say you're using a toothed belt for this. I suggest that the respective pulleys may be running out of sync' and slowly stripping the teeth. Try turning over by hand and looking to see if the teeth on the belt are riding up on one of the pulleys. The solution if this is the case and you have a jockey wheel is to adjust the jockey until synchronisation is achieved. Alternatively you could consider changing the pulleys and converting to V-Belts.
Hope this helps.

<hr width=100% size=1>Born Free!
Now I'm expensive

 

[roger]

Obviously with the Adverc and a high output generator you are putting a big load on the belt. You talk about a toothed belt. Are you meaning a toothed flat belt on toothed flat pulleys. This sort of system will take an enormous load.
You are perhaps outside the normal automotive engineering parameters. A good experimentally minded engineering shop might be useful. alternatively you can probably get a lot of info on the web under toothed grip belts

<hr width=100% size=1>Roger

 

[Avocet]

As has been said, it's unusual to find an alternator driven by a toothed belt (i.e. something like a car timing belt). Plenty of them have "v" belts with "teeth" on the inside but this is just a way of allowing the belt to flex round tighter bends without cracking while still presenting a decent surface area to the "V" pulleys. Anyway, I found the following programme on the Gates website as a free download and used it for my own aletrnator installation so it might be of some use to you:

http://www.gates.com/europe/designflex/

Their website has lots of helpful info but getting the design parameters will be tricky.

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[pvb]

Belt suggestions...

Bob, I assume you're using a toothed V-belt, not a flat belt. A single V-belt should easily drive a 75A alternator. If you're having problems, you need to ensure that (a) the 2 pulleys are the same profile, and (b) the belt matches the pulleys. The best quality V-belts I've found are made by Gates. You can get them online from <A target="_blank" HREF=http://rswww.com>RS Components</A> - go to "Mechanical" and then "Power Transmission".

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[Col]

As others have guessed, I think you are talking of a "V"belt with teeth on the inside??
If so, make sure you have the correct width belt. The belt is designed to run on the Side faces only, if it is bottoming out in the bottom of the pulley "V", ie belt too narrow, you will experiance the failures you describe. Also worth mentioning, make sure pulleys are free of rust.

<hr width=100% size=1><A target="_blank" HREF=http://www.arweb.co.uk/argallery/colspics> Cols Picture Album</A>

 

[cliff]

Not sure I have the picture correct but I understand you are driving the 75A alternator of the PTO using a toothed belt as in the type used for driving cam shafts etc. If this is the case have you checked the drive cog and the driven cog for compatibility? The tooth pitch may not be the same - slightly different causing the teeth on the belt to strip or the pto may move slightly when running - check for any movement in the PTO output flange / drive cog.

Also belt maybe too heavy, that is not suitable for tight radii pulleys / cogs.

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[andyball]

we've got 12 & 24 alternators & have looked into higher power ones.

Most manufacturers reckon a single 12mm belt is good for perhaps 80A on 12V or 1/2 that on 24V....above that use two belts or a wide "serpentine" type....this is likely the best bet by far if you.re running off a pto.

A 24V alt. at 28.8V pushing 75Amps is generating over 2KW of power, add friction & efficiency losses & that sounds a LOT of power for a single belt.

as others have said, "toothed" ones are made for extra flex if driving a small -under 80mm ,say?- alt.pulley.

Check the various manufacturers/suppliers sites yourself, but that was what I found.

Lots of info. on trawler world archives too, seems there are higher quality belts out there that will cope for longer than 30hrs (prob. not toothed), but re-engineering is the right way.

what's the pto speed/diameter compared with the crank pulley on the engine your 75A one came from?...presumably you had no trouble on that engine?






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[brianhumber]

Re: Go to Gates for info and belts

As others have said Gates have very good info on their web site.
Your application is well within belt drive parameters

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[Birdseye]

in the past i have found fenner power transmissions (try yellow pages) a very good outfit for this sort of problem. they supply drive belts to industry so power up much heavier loads than you are talking of here. incidentally, they are a good source of non premium priced replacements for the engine makers belts

<hr width=100% size=1>this post is a personal opinion, and you should not base your actions on it.

 

[steve_cronin]

Can I just check the configuration....

..I assume that the seond alternator is running on a seperate belt and not forming an additional turn on the existing one?

A few thoughts...

The new alternator should be run on a seperate belt by providing a duplex pulley on the crankshaft. However if the second alternator is the only item running on this second belt then the belt need not be tightened to the same tension as the original belt because the belt stays in contact for 180 degrees of each pulley giving greater grip. (pre-war cars with thermosyphon cooling and fan attached to front of generator had quite slack fanbelts by modern standards) Although tension can be reduced, the belt is now asked to flex through 180degrees twice per revolution and at quite a high speed this will accelerate belt fatigue. If fitting a second belt, an idler pulley to correspond to the water circulating pump is a good idea to avoid above flexing demand. I would think though that if you just slackened the new belt a little you would improve it's life significantly but the increased angles of flexing are I think, your main problem.

Incidentally, the Adverc controller doesn't boost the charge as others do, it merely provides battery sensing so I don't think that this is significant.

Steve Cronin



<hr width=100% size=1>The above is, like any other post here, only a personal opinion

 

[oldsaltoz]

G'day Bob,

Try one of the Gates "Green Line" belts, I have used them for years and they outlast any others.

I had a problem running an oil cooled Motorola alternator, it eating twin belts after only a few hours, I fitted new belts from most of the known manufacturers, even matched belts, but none lasted. Then I installed a set green line belts, they were still going 2 years later when the equipment was sold.

And, no, I have not got an interest in Gates, just find them the best, also installed on both my vehicles and work shop compressor.

Avagoodweekend......



<hr width=100% size=1> Old Salt Oz /forums/images/icons/cool.gif Growing old is unavoidable. However, growing up is still optional.

 

[Cantata]

Re: Belt suggestions...

Good point about maybe belt is too narrow. I once used a toothed v-belt 0.5mm less wide than spec and it destroyed itself in about 20 hours.

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[pvb]

Revised opinion...

Just noticed you said you have a 24v system. In this case, a single V-belt won't last long driving a 75A alternator. There'll probably be a lot of slip, which will cause rapid wear. I wouldn't expect this to cause the notched bits to break off, though, so you still need to ensure that the pulleys are identical profiles and that the belt matches the profile properly.

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[pvb]

Adverc question...

Are there different types of Adverc regulators? All the ones I've fitted certainly do boost the charge.

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[LadyInBed]

Re: Green Line

That sounds like a good endorsement to me, I think I will invest.
I have a 24v Alternator piggy backed off the 12v Alternator, so have had problems with belts.


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[MainlySteam]

Back you up on the Gates Green Line belts oldsaltoz, and add that in my experience in normal operation they throw off very little black dust in comparison to many other makes.

Just got home from your lucky country at 2 am this morning, lots of sniffles and coughing people in Tasmania so I brought back a stinkin unlucky headcold to spread among my fellow NZ'ers.

John

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